- #1
RyanBruceX
- 14
- 0
Homework Statement
In this diagram, the net force on the 1.0 mC charge is zero. What is the sign and magnitude of the unknown charge q? Please see attached photo.
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Homework Equations
F = KQ1Q2/r^2[/B]
The Attempt at a Solution
I have approached this by first determining the force required by “q” on the middle particle to maintain the system in its current position. Because the 2 bottom particles cancel in the “x” direction the combined force they place on the middle particle is 2Fy? And so “q” must also place a force of 2Fy but in the -y direction on the middle particle. So by this rationale I should be able to calculate the charge of “q” using q = (2Fy)(r^2)/(k)(Q1) where Q1 is the middle particle.
q = (8.65 x 10^6 N)(0.0009 m^2) / (9.0 x 10^9 N M2/C2)(1.0 x 10^-3 C) = 8.65 x 10^-4 C positive charge?
I am assuming I do not have to use the vector method to determine the force of q because it also has equal components in both the - and + x directions which cancel. So net force is just in the y direction and this is used to calculate the charge?
The magnitude of this charge seems low to me, I would have expected a more symmetrical charge. Should I be considering the forces between q and the bottom two particles?[/B]